Organism Color Changes Indicate Change in Salt Levels

Oct 29, 2009

By using a tourist, sight-seeing Zeppelin airship to study halophilic, extremophile organisms in the San Francisco bay salt ponds, scientists are looking for clues that could indicate the consequences of climate change through modeling ecosystem change.

The SETI Institute and NASA have teamed up with Airship Ventures, Inc. to use the only Zeppelin in the United States to track how reverting a hypersaline ecosystem (salt pond) back to its original state as a wetland can be used to develop a dynamic predictive model of microbial ecosystem change.

This model will be used to predict what happens when a system undergoing evaporation is transformed back to a wetland through dilution by the gradual introduction of marine Bay water. In reverse, this model could be used to predict what happens when a wetland undergoes evaporation and drying out.

"Wetlands and estuaries are critical habitats that may reflect early impacts of climate change. As climate changes wetlands dry out", says key SETI Institute scientist, Rocco Mancinelli, Ph.D. Both of these models have implications for global climate change through rising of the seas and flooding dry areas, to increasing temperatures causing other areas to become dry.

Specifically they propose to develop this model by examining the pigments of the ponds' organisms. The unique abilities of the Zeppelin to fly low and slow over the San Francisco Bay allow scientists to take high resolution spectra and images across the vast area to analyze pigment changes in the salt ponds as they change from hypersaline to marine.

The organisms inhabiting hypersaline ponds are red, making the pods appear red. Conversely, organisms in marine water are green, and therefore give marine water a greenish hue. As the ponds are diluted the salt concentration decreases and the number of red halophilic organisms lowers, and the number of green marine algae increases.

Not only does this investigation provide insight into the impact of climate change, but it allows scientists to study the organisms currently thriving in the ponds. It is rare that life has been able to flourish in such an inhospitable environment. This project has implications for understanding the future of life, an important astrobiology goal. In addition, studying the rate of change of this environmental system may shed light on the potential for extraterrestrial environments with similar conditions to be capable of sustaining life.

The SETI Institute is a non-profit scientific organization dedicated to research, exploration, and education in the field of astrobiology.